The present invention relates to communication networks, and more specifically, to providing a dynamic frequency tunable low latency chromatic dispersion compensator for latency-sensitive networks.
In optical communication systems, chromatic dispersion of light signals propagating over long distances causes light pulses to spread out as they travel along an optical fiber. Chromatic dispersion occurs because different spectral components at different wavelengths in a pulse travel at slightly different speeds. For example, in normal dispersion situations, short wavelengths (blue) travel faster than long wavelengths (red). First-order chromatic dispersion, D, is given in ps/nm-km by the expression:
  D  =                    S        0            4        ⁢          (                        λ          c                -                              λ            0            4                                λ            c            3                              )      In this expression, λ0 is the fiber's zero dispersion wavelength, S0 is the fiber's zero dispersion slope, and λc is the operating center wavelength. The resulting pulse spread can cause pulses in succession to overlap and interfere with each other, producing bit errors. The optical power penalty associated with first order dispersion, Pd, is given (in dB) by:Pd=5 log(1+2π(BDΔλ)2L2)In this expression, B is the bit rate, L is the link length, and Δλ is the root mean square (RMS) spectral width of the source. Dispersion can become a limiting factor in optical communication systems, since it grows worse for longer links and higher bit rates. Higher order dispersion effects and/or time varying dispersion effects can have differing impacts on transmission integrity. For example, transmitted wavelengths can experience a larger degree of change than others traveling through the same path, where the actual degree of change varies with respect to time. Additionally, ageing and voltage variations in transmission equipment can reduce the effectiveness of static dispersion compensation techniques.